Method of and apparatus for producing corrugated tubing



Nov. 29, 1960 R. H. GREENE ET AL 2,962,078

METHOD OF AND APPARATUS FOR PRODUCING CORRUGATED TUBING Filed July 16, 1956 INVENTORS RAYMOND H. GR EENE BY ELMER A ITT ATTOR NEYS Unimd t tes Patent METHOD OF AND APPARATUS FOR PRODUCING CORRUGATED TUBING Raymond H. Greene and Elmer A. Witt, Detroit, Mich., assignors to Calumet & Hecla, Inc., Calumet, Mich, a corporation of Michigan Filed July 16, 1956, Ser. No. 598,069

1 Claim. (Cl. 153-72) This invention relates to corrugated tubing and refers more particularly to a method of and apparatus for producing corrugated tubing.

One object of this invention is to provide an improved method of producing corrugated tubing.

Another object of the invention is to provide apparatus for producing corrugated tubing by the improved method which is composed of a relatively few simple parts and yet which is capable of producing high quality corrugated tubing at a relatively high rate of speed.

The tube formed by the method and apparatus of this invention may, for example, be employed in a heat exchange installation, the corrugation improving the heat exchange characteristics of the tube.

Other objects of the invention will become more apparent as the following description proceeds, especially when taken in consideration with the accompanying drawings, wherein:

Figure 1 is a top plan view of apparatus embodying the invention, showing a tube in operative relationship therewith.

Figure 2 is a front elevational view.

Figure 3 is a fragmentary view, partly in section, showing the cooperation between the corrugating member or disc and the pin within the tube.

Referring now more particularly to the drawing, a tube is indicated generally by the reference numeral 10. The rolls 12, 14 and 16 are mounted upon arbors 17 and are distributed about the axis of the tube 10, the tube being supported upon the cylindrical surfaces 19 and 21 of the two lower rolls 14 and 16. The axes of the arbors 17, and hence of the rolls, extend obliquely relative to the axis of the tube at the same angle, and at such an angle to the tube axis as to travel a helical path thereabout.

The roll 12 is provided with a relatively narrow disc 18 clamped to the front end by a nut 23. The disc extends substantially radially outwardly beyond the cylindrical surface of the roll 12 and its annular periphery is rounded as illustrated. The periphery of disc 18 is adapted to engage the outer surface of the tube and, when rotated, to apply a rolling pressure against the wall of the tube to press it radially inwardly along the helical path that the disc makes upon the surface of the tube. The periphery of the disc 18 is concentric with the axis of-rotation of roll 12, and the helix angle of the corrugation or fold 20 in the tube produced by the action of the disc thereon is the same as the angle that the axis of rotation of roll 12 makes with the axis of the tube.

The tube is rotated and advanced by the cooperative action of the cylindrical surfaces of the rolls 14 and 16 and the periphery of the disc 18 which frictionally engage the tube. The cylindrical surfaces of rolls 14 and 16 engage the uncorrugated portion of the tube. The cylindrical surface 25 of the roll 12 does not contact the tube to advance it as do the cylindrical surfaces of the other rolls. The cylindrical surface 21 of roll 16 is knurled, as shown, to provide a better frictional engagement and hence a more positive rotation and feed of the tube.

Extending within the tube at the rear of the corrugating disc 18, is an elongated cylindrical pin 22. The rear end of the pin extends beyond the rear end of the tube and is connected to a suitable anchorage (not shown). The front end of the pin has a transverse end surface at right angles to the axially extending cylindrical surface thereof and connected to the latter surface by a convex or rounded annular surface 24, as shown in Figure 3. This rounded surface 24 is disposed slightly to the rear of the corrugating disc 18 and cooperates with the corrugating disc in the formation of the corrugation 20.

In operation, the three rolls 12, 14 and 16 are rotated at the same rate of speed by suitable means (not shown). The cylindrical surfaces of the rolls 14 and 16 cooperate with the periphery of the corrugating disc 18 to frictionally engage and thereby rotate and axially advance the tube 10 in a forward direction. The disc 18 applies a rolling pressure to the outer surface of the tube along a helical path to form a helical radially inward corrugation or fold 20 along the helical path. The pin 22 cooperates with the disc in the formation of the corrugation. The pin rests upon the bottom interior surface of the tube, and the rounded annular surface 24 supports the convex portion 26 of the corrugation connecting the apex and rear wall of the corrugation at approximately the point of engagement of the disc 18 with the tube. The remaining interior portions of the tube at the front and rear sides of the point of engagement remain unsupported. Thus, the disc, in effect, folds or bends the material of the tube over and around the rounded end 24 of the pin to form the corrugation, and due to the fact that the remaining interior portions of the tube are unsupported, the corrugation is enabled to develop naturally in response to the rolling pressure applied by the corrugating disc. As a result, a very smooth regular corrugation is developed without undue wear or working of the material of the tube.

The knurling on the cylindrical surface of roll 16 provides a more positive rotation and feed of the tube due to the better frictional engagement therewith. It has been found that if the knurling is omitted, there is a tendency for the tube to slip in rotation with the result that fewer convolutions per inch of the corrugation are developed on the tube.

The drawings and the foregoing specification constitute a description of the improved method of and apparatus for producing corrugated tubing in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claim.

What we claim as our invention is:

Apparatus for forming a helical corrugation in a length of tubing, comprising a plurality of rolls angularly arranged to support and frictionally grip the length of tubing at spaced points about its circumference, said rolls being disposed with their axes oblique to the axis of the length of tubing and at an angle to the latter axis corresponding generally to the helix angle of the corrugation to be formed in the length of tubing, at least one of said rolls being driven to rotate and longitudinally advance the length of tubing frictionally gripped by said rolls, one of said rolls being in the form of an annular disc disposed to engage the length of tubing to apply a rolling pressure and form a helical corrugation in the length of tubing during the rotation and longitudinal advance thereof, a mandrel extending within the length of tubing in position to support the corrugation at approximately the point of engagement of said annular disc with the length of tubing, the end of said mandrel being rounded and supporting the convex portion of the corrugation connecting the apex and rear wall thereof, the remaining interior portions of the corrugation being unsu ported to enable the corrugation to develop naturally in response to the rolling pressure. 5

References Cited in the file of this pat ent UNITED STATES PATENTS 12,669 Cate Apr. 10, 1855 10 4 Fife July 15, 1890 Sammis Nov. 8, 1932 Novack July 25, 1939 Anthony May 10, 1949 Jones Oct. 10, 1950 Bornand Feb. 14, 1956 Penrose Dec. 24, 1957 FOREIGN PATENTS Great Britain July 24, 1939 

